Experimental investigation of the mechanical properties of BFRP bars in coral concrete under high temperature and humidity

The use of basalt fibre reinforced polymer (BFRP) bars in seawater concrete structures with all-coral aggregates is an effective solution to the problem of steel bar corrosion. However, the durability of BFRP bars in a real coral concrete alkaline marine environment has not been extensively investigated. In this study, the mechanical properties of BFRP bars in coral and ordinary concrete were investigated by using the accelerated erosion method in a laboratory environment. A total of 85 specimens were designed and produced. The BFRP bars were subjected to tensile testing to examine the degradation in their mechanical properties after being immersed in artificial seawater solution at indoor temperatures of 40 degrees C and 60 degrees C for 60 d, 120 d, 180 d, and 220 d. The results indicated that the tensile strength and ultimate tensile strain of the BFRP bars exhibited different degrees of degradation at various ages and environmental conditions, although the elastic modulus did not change considerably. The temperature considerably influenced the degradation rate of the tensile strength of the BFRP bars. Moreover, the degradation rate of the tensile strength of the BFRP bars in coral concrete was higher than that of the BFRP bars in ordinary concrete at the same ambient temperature. The experimental results pertaining to the microstructural characteristics of coral aggregates and the degradation mechanism of the mechanical properties of BFRP bars were discussed. Subsequently, based on the Fick and Arrhenius degradation models, the lifetime prediction of BFRP bars in coral concrete under a marine environment was conducted. The presented findings can provide a reference for the design and application of BFRP-bar-based coral concrete structures in the marine environment. (C) 2020 Elsevier Ltd. All rights reserved.